The proposed research involves isolation and characterization of an E. coli DNA topoisomerase I mutant. The aim of the work is to learn the role of E. coli DNA topoisomerase I, also known as omega protein, in E. coli DNA metabolism. It could be involved in one or more of the following processes: DNA replication, DNA repair, transcription, or recombination. Once a mutant deficient in omega is found, the effect of the mutation on E. coli macromolecular synthesis and other aspects of the cell's metabolism will be studied.